A novel method to measure diffusion coefficients in porous metal–organic frameworks

文献情報

出版日 2010-06-07

DOI 10.1039/B927601G

インパクトファクター 3.676

著者

Olexandra Zybaylo, Osama Shekhah, Hui Wang, Maxim Tafipolsky, Rochus Schmid, Diethelm Johannsmann, Christof Wöll

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要旨

We present a novel method to determine diffusion constants of small molecules within highly porous metal–organic frameworks (MOFs). The method is based on the recently proposed liquid-phase epitaxy (LPE) process to grow MOF thin films (SURMOFs) on appropriately functionalized substrates, in particular on organic surfaces exposed by thiolate-based self-assembled monolayers (SAMs). By applying the LPE-method to SAM-coated quartz crystals, the time-dependence of the mass-uptake of the MOF when exposing it to a gas is measured by a quartz-crystal microbalance (QCM). The homogenous nature of the SURMOFs together with their well-defined thickness allow to analyze the QCM-data using Fickian diffusion to yield the diffusion constant. We demonstrate the potential of this method for the case of pyridine diffusion within HKUST-1 (Cu3(BTC)2) MOF, for which the diffusion coefficient at room temperature is found to amount to 1.5 × 10−19 m2 s−1. Assuming a Fickian diffusion and a hopping mechanism, we yield a binding energy of 0.78 eV of the pyridine to the Cu2+ sites within the HKUST-1 MOF, a value in good agreement with the results of precise ab initio quantum chemistry calculations.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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